title: Daily and annually variation of unstimulated whole saliva flow rate and pH and their relation with body profile in healthy young adults.
abstract: OBJECTIVE
  To analyse pH and flow rate (FR) of unstimulated whole saliva (UWS), detecting their possible correlations both among themselves and with body profile; in addition to identify daily, annually and gender differences.
  
  
  METHODS
  Eighty-one (47 ♀; 34 ♂) healthy young adults (mean age 22.7±4.09 years old) were enrolled. Saliva was sampled using spitting method. The data were statistically analysed using Pearson's coefficient, ANOVA or Kruskal-Wallis test, Student's t test or the Wilcoxon-Mann-Whitney test.
  
  
  RESULTS
  The mean UWS/FR was 0.643 ml/min (range 0.164-1.656 ml/min; percentile 25 = 0.400 ml/min; percentile 50 = 0.643 ml/min, percentile 75 = 0.832 ml/min; median = 0.590 ml/min) and no significant differences were found in gender. The mean UWS/pH was 6.95 (range 6.06-7.91, S.D. 0.28, RSD % 4.08): pH was higher in males (7.02) than females (6.92; p = 0.009). The UWS/FR increased almost steadily during the day: from 0.593 ml/min at 9:00 to 0.669 ml/min at 17:00 (p = 0.04), the greatest increase was found between 9:00 and 11:00. Through the seasons the UWS/FR decreased from summer to spring with a difference of 0.048 ml/min (p < 0.05). The UWS/pH showed a slight increase between 9:00 and 17:00 (p < 0.05). There were little differences in UWS/pH among the seasons (max. 0.09; p < 0.05). Only a significant correlation between UWS/FR and pH was found (R = 0.20; p = 0.008).
  
  
  CONCLUSIONS
  We did not find correlations between body profile vs UWS/FR or pH. UWS/FR varies more widely than UWS/pH: maintaining a proper acid/base balance is an essential factor for the homeostasis of the oral cavity and probably this would explain the reason for the lack of the variables evaluated influencing UWS/pH.
authors.affiliation: Departement of Translational Medicine, Department of Health Sciences, and Department of Pharmaceutical Sciences; A. Avogadro University of Eastern Piedmont, Novara, Italy. pierluigi.fogliobonda@unipmn.it.
authors.forename: P L
authors.initials: PL
authors.lastname: Foglio-Bonda
authors.forename: M
authors.initials: M
authors.lastname: Migliario
authors.forename: V
authors.initials: V
authors.lastname: Rocchetti
authors.forename: F
authors.initials: F
authors.lastname: Pattarino
authors.forename: A
authors.initials: A
authors.lastname: Foglio-Bonda
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D012463:Saliva / Q000378:metabolism*; D012636:Secretory Rate; D055815:Young Adult